The Digital Audio Broadcasting Journey from the Lab to Listeners - the Czech Republic Case Study

Abstract

This paper describes the complex experiences and the results of the Digital Audio Broadcasting (DAB+) implementation in the conditions of the Czech Republic. It analyses the background of the EUREKA 147 program, its targets, and to what extent they were reached. The main focus is concentrated on the evaluation of the real steps which had to be done during the implementation process before the first regular broadcasting could be started and the difficulties encountered. The key point became experimental broadcasting "DAB Prague". It demonstrated the advantages of this new platform and gave the opportunity to test its functions and physical behavior in real conditions, under the different parameter settings. The important issue is the allocation of the band III by the National Regulatory Authority and the capacity of DAB+ multiplexes. The paper also demonstrates the experience from the setup of the DAB+ headend. It describes the content solution in context of using non-entropic audio coding, setting the codec algorithms and the way to use accompanying multimedia services. The results of the tests and measurements presented in this paper were used in the real project of the regular nationwide DAB+ network.

DAB+ Network Implementation in the Czech Republic and Impact of the Audio Coding on Subjective Perception of Sound Quality

“…The first regular DAB+ broadcasting in the Czech Republic was launched by Czech Radio on June 1, 2017 by fluent transition from the experimental mode. The experimental broadcasting, called "DAB Prague" [10], which preceded the launch, was used to test, measure and verify theoretical assumptions in real and specific conditions of the Czech Republic before the construction of the network itself [3]. The start of regular DAB+ broadcasting and the official launch of the "CRo DAB+" multiplex was made possible by the Resolution of the Czech Government No.…”

“…The main pioneer of radio broadcasting digitization and the implementer of this network became public service Czech Radio in cooperation with the network operator České Radiokomunikace (CRA). A series of measurements and tests were performed during the stage of experimental broadcasting [3] and this experience was used for planning and preparation of the regular broadcasting. The main attention was devoted to increasing signal coverage in the popula-tion and on highways, which was important because in-car listening represents a significant share of total radio listening.…”

“…Using HE-AAC v2 with Spectral Band Replication (SBR) and Parametric Stereo (PS) superstructures, the resulting coding efficiency is about four times higher than the previous MPEG2 [6] coding, used in the original DAB version. Even at a bitrate of 48 kbps, subjectively perceived high-quality audio transmission can be achieved in this case [3], [7].…”

“… Highly efficient audio coding has enabled the use of higher level of protection ratio FEC 2A instead of generally used FEC 3A, which is also referred to as "reference". This method generates an approximately +4 dB margin [3] over the standard level FEC 3A, which increased the usable signal coverage up to twice the area compared to the FEC 3A, under certain conditions. Generally, different FEC levels provide a different trade-off between the usable audio data rate and the robustness of the transmission channel.…”

“…This project was based on ITU-R Recommendation P.1546-2 for the frequency band 174-230 MHz [8], on the numerical modeling of the coverage and on the Czech Radio´s measurements and tests carried out before and during the construction of the network [3]. The construction of the network was divided into five stages, which were based on the chosen strategy and reflected the technological preparation and the state of international frequency coordination.…”